Analog Circuit Design

Figure 33.136 Conceptual Thermal RMS-DC Converter

The advantages of this approach have made its use popular in thermally based RMS-DC measurements. Typically, the assembly is composed of matched heater resistors, sensors and thermal insulation. These assemblies are relatively large and expensive to produce. Figure 33.137’s economical wideband thermally based voltmeter is based on a monolithic thermal converter. The LT1223 provides gain, and drives the LT1088 RMS-DC thermal converter.¹⁹ The LT1088’s temperature sensing diodes are biased from the supply. A1, set up as a differential servo amplifier with a gain of 9000, extracts the diode’s ...